People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

There are incurable diseases out there so rare, you could almost count those afflicted with them on one hand. In the video above, “10 Bizarre Diseases With No Cure,” AllTime10s shed some light on some of the most bizarre diseases ever encountered, including one that no human has ever suffered.

Sellars Disease

Mandy Sellars has the unfortunate distinction of having both a disease named after her, and being the only person on the planet suffering from it. Sellars’ legs are abnormally fat thanks to a faulty gene which makes her legs grow uncontrollably. Together they weigh more than 230 pounds, even though everything above her waist has grown as usual.

Tree Man Illness

Also known as Epidermodysplasia verruciformis, Tree Man Illness gets its name from the bark-like warts that grow all over a sufferer’s body. The illness is believed to be caused by a person’s low immune system not fighting the common infection HPV (Human papilloma virus). Today, it is known to affect only three people in the world, but up to 195 cases have been reported throughout history.

Vampire Syndrome

Vampire Syndrome (Hypohidrotic ectodermal dysplasia) creates thin skin that lacks pigmentation in its victims, leaving them looking like vampires. Those who suffer from the disease must avoid sunlight, and have fang-like teeth because of how it causes their teeth and hair to grow.

Progeria

More commonly known as Benjamin Button Syndrome, progeria causes sufferers to age 10 times faster than normal. The disease is caused by a mutation that occurs during embryonic development. Sufferers have above-average intelligence but their physical appearance is affected, with stunted growth, hair loss, shrunken facial features, and fragile bodies among the symptoms. Most progeria patients aren’t expected to live past 13 years old. The disease affects roughly 1 in 8 million births.

View the video above to learn more about rare, bizarre diseases without any cure.